Effect of Intravenous Lidocaine (1.0 mg/Kg) on Propofol ED50 and ED95 for Successful Double-Lumen Laryngeal Mask Airway Placement in Hysteroscopy Patients: A Randomized Controlled Trial

It has been demonstrated that administration of intravenous lidocaine promotes laryngeal mask airway (LMA) placement. This research aimed to evaluate the effect of intravenous lidocaine at a dosage of 1.0 mg/kg on the 50% and 95% effective doses (ED50 and ED95) of propofol required for the successful placement of a double-lumen LMA during propofol-fentanyl-based anesthesia in patients undergoing hysteroscopy. Eighty patients who underwent hysteroscopy were screened and randomly enrolled in either lidocaine group (group L, n=40) or the saline group (group S, n=40). The propofol induction dose per patient was established via an up-and-down sequential method. Under the guidance of bispectral index (BIS) value monitoring, the propofol doses required for the successful placement of a double-lumen LMA in 50% and 95% of the patients in the two groups (ED50 and ED95) were compared. The total propofol induction dose, awakening duration, and adverse outcomes were documented and analyzed. The propofol's ED50 was notably lower in the L group than in the S group (1.15±0.27 mg/kg versus 1.83±0.26 mg/kg; p<0.05, Cohen's d=2.56). The ED95 (95% confidence interval) of propofol was 2.04 (1.23-2.85) mg/kg in the L group and 2.64 (1.95-3.33) mg/kg in the S group, with a small effect size for the difference (Cohen's d=0.25). The total propofol induction dose in the L group was lower than that in the S group (p<0.05). There existed no variations in terms of awakening duration or incidence of adverse events. In patients who underwent hysteroscopy, post-propofol intravenous lidocaine at 1.0 mg/kg markedly reduced the propofol's ED50 in propofol-fentanyl-based anesthesia for successful placement of a double-lumen LMA without significant adverse reactions.